Plateau Star Tower: Chasing the mysteries of the universe at the Ali Observatory
2024-08-22
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During my postgraduate study, I used the 40cm telescope at the Ali Observatory to conduct scientific research related to asteroid photometry through remote control. It has always been my wish to go to the Ali Observatory for observation and learning. Fortunately, at the end of April this year, the research team sent me to Ali to assist in the installation and debugging of the 60cm binoculars.This made me very excited, but also very nervous: I was excited to go to Ali for field observations, finally being able to climb the plateau to fulfill my wish and see the spectacular sight of the stars falling on the plateau; I was nervous about the challenges that the high-altitude, cold and oxygen-deficient environment would bring to my body, and whether I could successfully complete the established work tasks. But why should the telescope be placed in a place with a harsh living environment on the plateau, especially in such a high-altitude, cold and oxygen-deficient environment in Ali?Ali here refers to the Ali region, located in the western part of China's Tibet Autonomous Region, in the hinterland of the Qinghai-Tibet Plateau, known as the "roof of the roof of the world". The average altitude of the Ali region is over 4,500 meters, making it one of the places on earth closest to the sky.Before we understand why Ali was chosen as the site of the observatory, we need to briefly understand the basic principles of ground-based astronomical observation. Ground-based astronomical observation is to receive signals from celestial bodies through ground-based telescopes, and there will be inevitable losses when celestial body signals pass through the atmosphere. The less and more stable the atmosphere above the site, the better the quality of the received signal. In addition, artificial light sources must be avoided to ensure that the site has a high number of sunny days and no strong winds and sand, otherwise it will affect observations in optical and other bands.▲ Figure 1Schematic diagram of astronomical observation bands and atmospheric absorption windows. Source: China Antarctic Astronomy Center
Because of its dry and thin atmosphere, extremely high altitude, 82% clear-to-night ratio and almost zero light pollution, Ali has the conditions to become a world-class astronomical observatory and an ideal place for astronomical researchers to look at the sea of stars and explore the distant universe.From 2002 to now, our predecessors have overcome numerous difficulties and through remote research, field surveys, fixed-point monitoring and site construction, the astronomical observatory was selected and built at the top of Jiamaerdeng Mountain (32.325°N, 80.027°) south of Shiquanhe Town, at an altitude of about 5,100 meters, and finally the "Star Tower" was established in Ali. Today, the infrastructure of the Ali Astronomical Observatory has been almost completed, and some telescopes have carried out observation missions for different scientific targets.▲ Figure 2Panoramic view of the Ali Observatory. Source: Xinhua News Agency
What are the challenges in assembling and debugging the telescope in Ali?
Although the high altitude and thin air in Ngari are conducive to astronomical observation, they pose physical challenges to researchers. I have never lived at high altitudes before, so in order to adapt to the high altitude, I stayed at Lhasa Gonggar Airport, which is 3,570 meters above sea level, for one night to do some short-term adaptation. I did not feel any discomfort that day, but when I arrived at Shiquanhe Town in Ngari the next day, the beautiful snow-capped mountains and the suffocating feeling brought by the thin air instantly stimulated my sensory nerves.▲ Figure 3Snow-capped mountains in Ngari Prefecture. Photo provided by the author
Without taking a break, we drove to the observatory to assemble the telescope that night. The assembling of the telescope is a job that requires high precision and collaboration. Every tube and every accessory must be carefully installed. We basically completed the assembly of the telescope on the first day. This was thanks to our previous full preparation. In fact, we had already assembled and debugged the telescope in Nanjing before mailing it. This included but was not limited to checking every assembly detail of the telescope, the installation settings of the control software, and a detailed installation and debugging plan.The wind speed at the Ali Observatory was very high that day, which brought great challenges to the hoisting work. In such an environment, the crane master was operating almost in a completely blind spot. For a delicate device like a telescope, the slightest carelessness could cause irreversible damage. We had to work closely with him to ensure that every step went smoothly. It was not easy to stay focused and calm amid the interference of wind speed and the physical discomfort caused by altitude sickness. With the tacit cooperation and full understanding of the equipment that we had practiced repeatedly in Nanjing, we successfully completed the installation process of the telescope. However, during the debugging process, it was discovered that the main mirror was out of the slot due to improper transportation or installation, so that it took a long time to debug and discover this problem. Fortunately, this problem is solvable.▲ Figure 460cm binoculars hoisting diagram. Photo provided by the author
The next day, we officially started debugging the telescope. However, both I and the computer had severe "altitude sickness". I had a liquid oxygen bottle to deal with it, but the originally debugged computer could not work properly anyway. This resulted in us having to change to a spare computer and reinstall and set up the software. In addition, debugging is always done at night, and the nights in Ali in April are cold and windy, which makes debugging even more difficult.▲ Figure 5The assembly process of a 60cm binoculars. Photo provided by the author
The debugging of astronomical telescopes is always like this. Although various considerations were made before departure, accidents always occur continuously. In addition to the high-reflection strikes such as data cables and computers during the debugging process, we also encountered problems such as the inability to adjust the optical axis and focal plane. After several unsuccessful attempts, the high-reflection also caused the brain to be in a state of hypoxia, making it more difficult to think clearly and clarify logic. Later, when I checked the telescope debugging log, I found that some very small problems took a lot of time to solve at the time. For example, the poor image quality was only because the camera mount was a little loose. Fortunately, we have basically completed the installation of software and hardware, and the debugging of optical axis and focal plane can be completed by remote cooperation with engineers and teachers stationed at the observatory.Although the entire debugging task was not completed, after a short 3-day work, the 60cm binoculars were successfully assembled and some debugging was done, achieving the basic goal.▲ Figure 6The posture of the 60cm binoculars during debugging. Photo provided by the author
This 60cm binocular telescope will enter the working stage in the near future, and its main task is to conduct sky surveys of asteroids. By splicing the fields of view of the two telescopes, it forms a larger observation field of view, which can cover a wide area of the sky in a short time. This design greatly improves the data collection efficiency of the telescope, especially in monitoring and searching for new potentially dangerous asteroids. Compared with traditional monocular telescopes, it can complete sky surveys faster. Through continuous observation, we can accurately track the orbits of asteroids and promptly warn of the risk of impact with celestial bodies that may threaten the Earth, which also contributes to the establishment and improvement of my country's near-Earth defense system.Alibaba ResearchInteresting experiences during the trip
For me, the scientific research trip at the Ali Observatory is not only a work experience, but also an excellent life experience. I just took a car to debug the telescope. If I was tired, I could rest in the observatory. If I had altitude sickness, there was oxygen supply equipment. If I was cold, I could go to get warm. I can't imagine how hard it was for our predecessors to come here to inspect the station site, and I can't imagine how the Ali Observatory was established. They overcame all difficulties to make our present convenience possible. I pay tribute to them again.The resident teacher at the observatory told me that there were many fossils among the rocks dug out during the construction of the station, but unfortunately we were basically busy assembling and debugging the telescope, and the altitude sickness left us no time and energy to look for fossils. However, I still saw a few beautiful marine fossils in the supermarket in Shiquanhe Town. Time and space have changed, and the sea has become a mountain, which is awe-inspiring.▲Figure 7: One side of the mountain top of Ali Observatory. Photo provided by the author
I thought there wouldn't be any animals here, but on our way down the mountain, I often saw wild rabbits jumping around and sparrows flying in panic. I realized that this place that looked desolate during the day was not dead, and the tenacity of life was moving. On both sides of the road back to Shiquanhe Town, the government began to plant a large number of trees. I don't know their survival rate, but I believe that this place will be full of vitality in the future.▲ Figure 8Newly planted trees on both sides of the road when returning to Shiquanhe Town. Photo provided by the author
The altitude of Shiquanhe Town is also as high as 4,300 meters. The altitude sickness made my whole body ache and my appetite lost. I didn’t try the local food carefully. I only remember that the local teacher recommended a lot of it. But I was satisfied with this trip. When I lay under the starry sky at the observatory, the extremely strong sense of comfort filled my whole body, and even made me forget the pain caused by the altitude sickness.The stars are shining brightly, telling the secrets of traveling through time and space; the vast earth carries the desire to see into the universe. Human beings' desire to explore the unknown universe has never stopped, and the story of the Ali Observatory is still going on. We look forward to it bringing more scientific discoveries.With the stars above our heads and the ground under our feet, the beauty of this mysterious land of Ali lies in the human desire and dream for the universe it carries, as well as the magnificence of its natural scenery. I hope everyone will have the opportunity to personally experience the charm of this land and feel the tranquility and contemplation under the starry sky.
Mozi was a famous thinker and scientist in ancient my country. His thoughts and achievements embody the early scientific buds in my country. The establishment of the Mozi Salon aims to inherit and carry forward the scientific tradition, advocate and promote the scientific spirit, improve citizens' scientific literacy, and build a social atmosphere that respects science.
Mozi Salon is aimed at the general public who love science, have a spirit of exploration and curiosity. Through face-to-face public activities and various new media platforms, we hope to let everyone understand the world's most cutting-edge scientific progress and most advanced scientific ideas, explore the secrets of science, and feel the beauty of science.
The Mozi Salon is hosted by the Shanghai Research Institute of the University of Science and Technology of China and the Nanqi Quantum Technology Exchange Center of Pudong New Area, and is supported by the USTC New Alumni Foundation, the University of Science and Technology of China Education Foundation, the Pudong New Area Science and Technology Association, the China Association for Science and Technology, and the Pudong New Area Science and Technology and Economic Committee.
